full screen / videoFor each city, this map shows the date of the earliest recorded population figure, which is not necessarily the date when the city was founded. The size of each dot corresponds to its population at that time.

By 2030, 75 percent of the world’s population is expected to be living in cities. Today, about 54 percent of us do. In 1960, only 34 percent of the world lived in cities.

Urbanization didn’t begin in the 1960’s. But until recently, tracking its history much further back than that was a challenging task. The most comprehensive collection of urban population data available, U.N. World Urbanization Prospects, goes back only to 1950. But thanks to a report released last week by a Yale-led team of researchers, it’s now possible to analyze the history of cities over a much longer time frame.

The researchers compiled the data by digitizing, geocoding, and standardizing information from past research published about historical urban populations. The result is a clean, accessible dataset of cities, their locations, and their populations over time, going as far back as 3700 B.C.

As the authors of acknowledge, the data has a number of limitations and is “far from comprehensive.” Certain parts of world are better represented than others, and some well known cities do not appear until centuries after they were founded. That said, for such an ambitious project (the historical populations of every city ever built anywhere in the world), I think they managed to piece together an impressive amount of data.

Edit: In response to a few questions regarding the definition used here for “city,” below is some more information from the study. The researchers compiled the data from two original sources: Four Thousand Years of Urban Growth: An Historical Census by Tertius Chandler and World Cities: -3,000 to 2,000 by George Modelski. Both original sources define cities based on population, though they use different thresholds.

“Chandler included only the largest cities for each time period: cities with populations over 20,000 from AD 800 to AD 1850 (excluding Asian cities which had a 40,000 population threshold for this period), and cities with populations over 40,000 after AD 1850 for all locations.”

“Modelski used different minimum thresholds from Chandler for different eras to define a city:

Ancient (3500 BC to 1000 BC):≥10,000 inhabitants

Classical (1000 BC to AD 1000):≥100,000 inhabitants

Modern (AD 1000 onward):≥1,000,000 inhabitants”

If you would like to go through the data yourself, you can find a spreadsheet for each original data source in the report. Also included is an R script for combining it all.

Or if you just want to explore a bit, here is the same data from the map above, plotted using Mapbox.

I'm an NYC-based entrepreneur (my newest project: Blueshift) and adjunct instructor at UPenn. I'm fascinated by data visualization and the ways that data is transforming our understanding of the world. I spend a lot of time with my face buried in Excel, and when I find something interesting I write about it here and also as a Guardian Cities and Huffington Post contributor.More about my background

It’s a double whammy – huge increase in the rate of population growth and the percentage of people living in cities.

Deb Inity

Really? You can show when Buddha dies, but not mention Christ at all? What do you think BC means? The years you’re showing measure time as “Before Christ”, then “Anno Domini”. You guys can try to eliminate HIm or make Him as unimportant, but you’re just spitting in the wind. Sad.

http://metrocosm.com Max Galka

Stop. You can’t point out my use of the “Before Christ” dating system (vs BCE/CE) and claim I’m trying to “eliminate him.”

RajeevS

Please don’t be offended but Jesus was a pygmy when compared to Buddha in intellect.

http://raaakshaseeyam.blogspot.com Raakshasan

May be because Buddha is a Historical Figure, and Jesus is a Mythological figure.

billracine

http://www.catholic.com/magazine/articles/did-jesus-exist – There’s actually quite a bit of evidence that Jesus did exist. Secondly, notice how rapidly the world expands (cities sprout) after 1AD – much of this was due to Christian influence working to spread Christianity to the entire world.

Hoku

What’s going on with Cincinnati and St. Louis?

http://metrocosm.com Max Galka

They were built at the location of Native American settlements. The one where St. Louis is now was known as Cahokia.

Hoku

Right, but Cahokia is on there later. Great graphic either way.

http://metrocosm.com Max Galka

I stand corrected. Cahokia was apparently across the river from where St. Louis is now. Perhaps there was a different Native American city on the St Louis side.

Mark

Since the Cincinnati and Chillicothe dots appear in the 1420’s I would guess those are cities from the “Fort Ancient” people. It’d be interesting if that could be confirmed. It’s definitely a cool map, I’d love to get more info on each of the earlier US dots. https://en.wikipedia.org/wiki/Fort_Ancient

It doesn’t show up at 2000. Lima appears on this map at 1600. Besides, this map isn’t about when it was founded or first settled. Didn’t you read the explanation above?

“Chandler included only the largest cities for each time period: cities with populations over 20,000 from AD 800 to AD 1850 (excluding Asian cities which had a 40,000 population threshold for this period), and cities with populations over 40,000 after AD 1850 for all locations.”

Real.WK

Your data is VERY inaccurate. Most of dates of cities in Russia/Ukraine are not correct.

http://metrocosm.com Max Galka

As mentioned above, “For each city, the map shows the date of the earliest recorded population figure, which is not necessarily the date when the city was founded. The size of each dot corresponds to its population at that time.”

Bada

“For each city, the map shows the date of the earliest recorded population figure”

I think there are population figures recorded for London or Paris earlier than 2000 AD though. I know you didn’t compile the data yourself, but it seems to me like the dates shown in all of western Europe show that the original data, however useful it can be, is very poorly fit for this visualisation.

tomclarke

I imagine that the decision to go for the first census date made sense because of all the myths surrounding the founding of great cities. Unfortunately, it leads to quite a lot of surprises. Like Barcelona appearing around 950 AD, nearly a thousand years after its name was formalized by the Roman administration as ‘Barcino’. And probably all the other comments complaining!

Anyway, it’s an interesting idea.

http://metrocosm.com Max Galka

Yes. In fact I’ve been to a museum in Barcelona that takes you underground and lets you walk around the old Roman ruins. Pretty cool experience.

You’re right, some cities do not appear in the data until a while after they were founded. Though for the vast majority of cities I’m familiar with, the dataset gets pretty close to the founding date. For such an ambitious project (the historical populations of every city ever built anywhere in the world), I think they did a pretty good job.

BorgWorshipper

That is really cool. Interesting how North and South American tribes coalesced into cities independently. It is easy to see network effects in North Africa/Eurasia.

What is up with that Moses bit? Most scholars and historians dismiss that story and character.

http://metrocosm.com Max Galka

Thanks! The thought behind the map was to tie together historical events that most people only know in isolation. That’s a famous one so I thought it would be interesting to add some context to where and when it takes place. In hindsight though, I wish I had just left out all of the religious references — think it may give the wrong impression about what the whole thing is about.

http://desativadoporpoucouso.blogspot.com Agronopolos

São Paulo (or Sao Paolo) funded in1554

Milos Kostic

Map isn’t true and correct enough. Focus better on smaller region and do it prcisely then the whole world map.

Hey

Nothing for Somalia? Mogadishu alone is 2000 years old, not to mention the Land of Punt and the numerous 1st century CE city states of the Somali coast mentioned in the Periplus of the Erythrean Sea.

DAS

You are missing the Vedic City called ‘Dwarka’ in modern days’ state of Gujarat in India.
It was submerged in water more than 10000 years ago.
They found the the structure not so long ago a few miles away from the land beneath the ocean.

Bryan Johnson

Dwarka was not a city more than 10,000 years ago. It’s just not possible. 10,000 years ago, people were hunter/gatherers. Until the agricultural revolution and domestication of animals there wasn’t even such a thing as a small town or village.

greetbigball

what makes a place a city? i noticed that somehow the pyramids were built BEFORE the first egyptian city? that just makes no sense

http://metrocosm.com Max Galka

The definitions used for city are explained in the study. Now added into the post.

Why is Jericho missing?
According to archaeological evidence, it’s the oldest city in the world (permanent city settlement circa 9600 BCE).

http://metrocosm.com Max Galka

Can’t speak for the researchers who prepared the data, but I would imagine there is not enough evidence Jericho was actually a “city” back then.

RajeevS

This map seems based on Judeo-Christian mindset where they try to show civillization began in mid-east which is not true. The latest discovery puts in on Indus. They should not forget that almost 40% thru ages have lived in India and China so level of urbanization in these countries must be much more than sparsely populated mid-east and recently populated Europe. Please come out of judeo-christian centric worldview. Before 1600s west was in pits except for period under non-christan Greece and Rome.

http://metrocosm.com Max Galka

Stop. It is generally accepted that civilization began in Mesopotamia and Europe does not even appear in the map until halfway through.

SickofPC

So you mention the rise of Muslims and the Jews leaving Egypt, but nothing of the birth or crucifixion of Christ? That’s the whole reason your map changes from BC to AD.

http://metrocosm.com Max Galka

The map is not about religion or calendar systems. It is about cities. And as important as his life is, it doesn’t have much significance to what is going on in the map and it’s also the one ancient historical date that everyone already knows. You mention the BC/AD dating system is if it were a given, but I chose to use it instead of the more politically correct BCE/CE system.

BC and AD are politically correct. It should be BCE, Before Current Era, and CE, of Current Era.

Slowly Rotating

Scholarship! There was no “Mayan Empire.” Firstly, the term Mayan refers only to the family of languages that are spoken by the Mayas. All else is Maya. Secondly, they never formed an empire, but rather a civilization of autonomous city-states much like the Greeks had. HeroesoftheMaya.org

http://metrocosm.com Max Galka

Touché

joed1015

I can’t believe how many complainers are commenting below.

Hey

Not sure why my comment was deleted but once again, the total neglect of the East African coast, in particular the numerous Somali city states described in the 1st century CE Periplus of the Erythrean Sea is a bit strange. Malao (Berbera), Mundus (Heis), Avalites (Zeyla), Opone (Hafun), Sarapion (Mogadishu) to name a few are pretty well documented. Shocking admission.

Albert Ruiz

Your comment was not deleted. I see it right here in response to another comment. This map and the study where the data is from do not claim to be the end-all-be-all for every city, everwhere, for all of history.

If you know of a better dataset, build your own map.

BAdkins

hear, hear, many comments are inappropriate. There were qualifications in the beginning, fascinating compilation! I am glad he put in the the religious dates as religion has much to do with where people lived either by choice or by happenstance. As previously stated by someone, this is what the internet is for, and I agree with Albert, if you don’t like this map or presentation, by all means build your own map!

Cherry Warr

well I find it fascinating and appreciate the work and time you put into it. Is it perfect? meh…but is it thought provoking and accurate enough to further the conversation along. Thank you so much! This is what the internet should be used for…sharing information in an easy to understand and engaging way.

Thomas Ellis

No one claims this to be a ‘see-all, do-all’ map. This is the ‘most comprehensive’ based on recorded populations. If it is not enough for you, make a better one.

Pradipa PR

“Make a better one” is the stupidest and laziest way to dismiss valid inputs and criticism.

Albert Ruiz

I think the point is that some of the comments below are not really valid criticisms. It’s one thing to give constructive input about what it could do differently. It’s another thing to complain about it not including a particular city, as if a comprehensive map of every city ever built were even a possibility.

Anibal Guerra Karekides

Panama City was the first city in the Pacific side of the Americas (1519). Need to update this map.

http://metrocosm.com Max Galka

No, the map is just the messenger. The data comes from the study mentioned above, which the researchers acknowledge is “far from comprehensive.”

Still, I’m pretty sure Panama City wouldn’t have qualified as a “city” in 1519. Even by 1600, there weren’t more than a few hundred Europeans living in the entire U.S.

Albert Ruiz

Awesome work! Inherrently interesting data, visualized beautifully.

osvaldopiazzolla

I find it striking that until very late in History, all the cities are
located nearly at the same latitude. Would be interesting to mix with
the climate change over history (but during the same period of time) interactive map from the same author.

http://metrocosm.com Max Galka

Good suggestion

mohammed

wow thats amazing!!

Nick Lacey

Hello! Thank you – very interesting. I have been looking at a lot of ancient sites on Google Earth. Several points from this:

– None of the ancient sites in the Ukraine such as Nebelivka, that were for the most part built of wood and therefore have left very little traces compared with cities in Mesopotamia. It is arguable that the Ukraine is one of the great cradles of civilization
– None of the later Scythian cities, such as Gelonus.
– The population of the steppelands in general is largely overlooked, despite this region being a huge source of population movement causing great upheavals throughout history – Scythians, Sarmatians, Goths, Alans, Huns, Slavs, Magyars, Mongols, Tartars to name but a few.
– No pre-Roman Celtic settlements listed
– No Etruscan cities prior or contempory to the rise of Rome, such as Veii, or the Magna Graeca cities of the mainland, such as Locri and Sybaris.
– What is also interesting along with when a city starts is when it ends and sometimes restarts (and often slightly relocated). In the case of Syracuse the ancient city limits were enormous compared with the modern town. This is similarly true in places like Akragas-Agrigento, Tunis-Carthage, and at places like Termez and Merv in Central Asia. Many of the cities of Mesopotamia lasted for as long as the Euphrates, Tigris or one of their tributaries provided fresh water – as the rivers shifted their courses, settlements were abandoned and the region arguably has the densest number of ancient cities for that main reason.
– How difficult it is to gauge the populations of ancient settlements, particularly when trying to establish the limits of a city, the population density within its defensive walls, and the extra-mural populations of cities and where their limits end and the rural population begins. For example, figures of around 1million for Rome at its height are given, but that would mean a population density of around 80,000 per square km within its later Aurelian walls and that just does not seem feasible (I generally work on 20,000 per square kilometer).
– Deciding what constitutes a “City” from the general mass of urban developments.

Thanks! 🙂

http://metrocosm.com Max Galka

Was not aware of the early civilizations in Ukraine. Something I’m interested to look into.

Completely agree about the Steppe societies. They are mostly overlooked by history, but they were consistently among the world’s most influential for thousands of years. Though as nomads they did not build cities, which is why they are not well represented on this map.

Yes, there is some subjectivity in deciding were one city ends in time and where another begins. Surprised that Tunis and Carthage are not considered separately since I don’t think their borders overlap much, if at all. The data includes ongoing population figures which were not used for this map. It would be interesting to look deeper at the progression of specific cities.

Added the definitions used for “city” into the post. People can’t even agree on the definition of and geographic limits for cities in the present. Can only imagine how much trickier it is for cities thousands of years ago.

Appreciate the smart feedback. Thanks.

Nick Lacey

Hello – thanks for the response!

Nebelivka and Talianki are the two main sites I am aware of. They are around 6,000 years old – putting them at the very start of your chronological map. They were huge cities, easily the equal of anything prior to the modern age. I actually suspect the eastern and western extents of the Eurasian steppeland to be one of the cradles of civilisation as they were readily suitable to both agrarian and livestock farming, but were – as ever – vulnerable to surprise attack by mounted enemies. I think the Indo-European languages attest to this ready and longstanding connection of this enormous geographical area and modern archaeological techniques and the like will continue to reveal more surprises.

Truly “nomadic” cultures are quite rare and there are a number of cities that were built at both the eastern and western extremes of the great Eurasian steppe – places such as Atil and Saray on the Volga, and Sanggyeong, Shangjing and Bairin in the east. The Volga Bulgarians also built a number of very large cities – such as Bolghar and Kazan – in the early medieval period, and there are a good number of ancient cities strung along what is traditionally refered to as the Silk Road routes, some famous, like Merv, others not, like Navekat. Gelonus at Bil’s’k in Poltavs’ka oblast has an area that was surrounded by pallisades and ditches of around 10km x 4 km, an area 3 times larger than Rome, and this was a Scythian – nomad – city.

I think that any cities on the Eurasian steppes are very exposed to attack by other mounted cultures – be they true nomads or semi-nomads and so what tends to happen is that cities such as Gelonus develop and then are destroyed. Because they are mainly wood, they leave little trace. There are not hundreds, but there a good number, with plenty of smaller ancient fortified towns in between. We are somewhat ignorant of them in the West, particularly given our current dreadful attitude towards the countries that contained these ancient civilisations – such as Iraq, Afghanistan, Iran, and the other central Asian countries. Places such as Termez and Balkh and Qocho and Bhitagor and Goor were great cities that most people know nothing about.

Carthage is essentially the Le Kram and La Marsa districts of the modern city of Tunis (so named after the Punic civilisation of Carthage) and is, again, enormous (and considerably larger than Rome). Even though this was a stone-and-brick city, little remains. Life goes on and so the building materials of yesteryear become the new houses of today – walls get torn down, moats get filled in and so often only the most stubborn of foundations remain.

There are also a number of very ancient cities on the steppes north of China. They are difficult to find and even more difficult to get decent information on! India also suffers from a lack of reliable information

But from what I have been looking at my conclusion is that if the land historically and for a prolonged period:

1) had year-round drinkable water
2) was fertile and capable of supporting crops or livestock for more than 9 months of the year
3) was defendable

Then people will have lived there in a permanent settlement at almost any point in history. Just count the number of Iron Age hillforts in southern Britain to see how even in that age there was a large and diffuse population.

Point 1 is utterly essential and it is the reason why you will see one hill in somewhere like Greece covered by a city and another that looks easier to defend not. It is the reason for the collapse of many of the cities in Mesopotamia.

Point 2 is important because there were not large populations in places such as Germany, Poland and in the coastal regions of Italy because they were not ready for supporting farming – Germany was forested and Poland and the coasts of Italy were swampy.

Point 3 is the key difference between cities within the last 100 or so years and 99% of all settlements previous to the modern era. Attack by foreign armies and one’s own neighbours has always been and remains the greatest threat to life and prosperity to any society. But with the advent of modern weaponry, the nature of defensive systems around cities has totally changed and we no longer need to build on easily-defended terrain. Ancient cities were the domain of a region’s elite and so they did not need to be large as large often meant difficult to defend and full of people you may well not like and who want to take your wealth. Some big cities such as Rome grew beyond their innate defensive positions (the Seven Hills in Rome’s case), but the majority of settlements on the continent were on higher ground or other easily defended locations. This, of course, limits the size to which a settlement can grow, as amply demonstrated by looking at Italian cities perched on rocky hillocks, and later German cities bound by their defensive walls.

Modern criteria are different:

1) Accessable via multiple modern transport communication – road, sea, air.
2) Must be economically viable as modern cities are obliged to make wealth in a wider geographical context.
3) Can reliably and on a large scale be supplied with energy and be capable of removing all types of waste.

The nature of cities has changed considerably in the last 200 years and we now find it difficult to comprehend the nature of ancient cities born of our past requirements because the patterns of our lives have changed according to our new needs.

disqus_vz1CSxjXQy

This Map is not correct when it comes to Vietnam. The Author did not study Vietnamese history (For example Dai La – was inhabited at least in 3000 BC – which became Thang Long in 1013 then became Hanoi in 1831. Many other cities were created long before that, i.e. Co Loa (capital of Van Lang) was created previously, but was conquested by Thuc Phan in 258BC…..). If his doe not time to read book, just simply check Wikipedia for Ha Noi to see….

http://metrocosm.com Max Galka

Please read the post before commenting. The data is not comprehensive, does not represent the cities’ founding dates, and was not compiled by me.

Whatever

The problem with “the first map” is we have to take it
as real history of civilization until someone in 100
years,and millions of $ in grants, comes up with a new map.

I don’t deny Galka’s well intention and efforts, but the map
will mislead many young people who do not read history.

Сергей Торпс

Where on earth did you find supposedly ‘exclusive info’ that Moscow was established in 1337???? cia archives? )
The official date of the city’s establishment is 1147. Correct it pls.

Running Reality

This is a great project! Thank you for doing the work to bring this research data into a straightforward and easy-to-use format. We are trying something similar over at http://www.runningreality.org and we understand how hard it is to get a good, solid, reliable data set on the ancient world and also how hard it is to bring that data to the web in an accessible way. We have been filling in nation, city, and battle data from 3000BC to today and slowly starting to work our way down to historical streets and buildings in select cities like Rome, London, Babylon, Carthage, and NYC.

http://metrocosm.com Max Galka

Cool project. Is the map build on Leaflet?

Running Reality

The app version is a world history model with completely custom engine to be able to do any date in history with a fully editable data set. The web version is a read-only way to view the world history model; it uses a custom client/server engine that feeds an OpenLayers2 browser renderer.

http://metrocosm.com Max Galka

Well done. Very ambitious project.

Gabriel Alves Brandão Machado

Not much accurate
.

SolutionOriented

Your map is an excellent beginning for obtaining a temporal perspective for the evolution of cities. I would only ask that you review your data from Latin America. My research suggests cities of greater than 20,000 far earlier than you have depicted.

marco

Interesting work. Good start. Why are all locations of early Egyptian cities (e.g. 3100 BC) misplaced on the map (none in the Nile valley)?

http://metrocosm.com Max Galka

I see the confusion. 3100 BC is when the first Egyptian dynasty begins. Though the first Egyptian city doesn’t appear until 2500 BC.

Louis Bausone

Exactly. Egypt is showing up in Iraq.

Nathaniel Mayes

A huge omission that i notice is recognition of the African Kingdom of Aksum, mentioned by the prominent Persian philosopher Mani (210-276 A.D.) as one of the four great empires of his time (210-276 A.D.), along with Rome, Persia, and China. Arguably, Aksum was the 1st empire to embrace Christianity. Aksum was deeply involved in the trade network between India and the Mediterranean, and became the principal supplier of African goods to the Roman Empire. Aksum minted its own currency by the late 3rd century, and under King Ezana (~320-360 A.D.), it was the first state ever to use the image of the cross on its coins. Aksum is also the alleged resting place of the Ark of the Covenant and the home of the Queen of Sheba. The late Pre-eminent scholar Dr. Stuart Munro-Hay conducted extensive modern research on Ethiopian history, including, among others: Aksum: an African Civilisation of Late Antiquity; and The Quest for the Ark of the Covenant: The True History of the Tablets of Moses. In ancient times Aksum is also, like what Mr. Hey referenced below re: the Somali coast, mentioned in the first century C.E. Periplus of the Erythraean Sea as an important marketplace for ivory, which was exported throughout the ancient world.

Michael_Rogers

In Australia, Melbourne appears before Hobart. European settlement began in Hobart some 30 years before it started in Melbourne,

Francesco Bruno

It’s incredible how much we look like a virus spread

http://metrocosm.com Max Galka

Agreed

Javier Lizarzaburu Montani

Good morning there. I saw with true fascination the beginning of this video, until I noticed a serious gap in the information. The first civilization in the Americas is Caral, some 5.000 years ago, and the only one to have developed without any known contact with other civilizations. Am attaching a link from Unesco about it. It would be good if you consider the possibility to update your information. http://whc.unesco.org/en/list/1269. Many thanks

http://metrocosm.com Max Galka

Thanks for passing it on Javier. I see UNESCO does describe it as a city, so perhaps it does belong. If it wasn’t clear from the post, this is not my area of expertise. The data comes from a recent study. And the authors are careful to point out the list is not comprehensive.

Mike McC.

I did notice some interesting things that puzzle me. The article discusses the Chandler and Modelski thresholds for a ‘city’ but doesn’t appear to state what criteria *you* use to put a ‘city’ on the map? There is a large difference between their two thresholds, huge in later years. For example, Dublin appears on the map in 1050CE, but it is listed with a population of 4,050 – that doesn’t meet either criteria.

Also, Barrow (Alaska) appeared around 1900CE with a listed population of 56,000. Is that population correct? Barrow (as a modern city) only exists because of oil and the pipeline and even today it only has a population of 4,000+ (according to Wikipedia).

I noticed that Constantinople(36,000 pop.) appeared on the map around 100BCE… 400 some years before the emperor after whom it was named. (Perhaps Byzantium never was a ‘city’ and it was already a ‘city’ when it’s named changed to Istanbul.)

Regardless, a very interesting map; I’m glad I found it.

varifrank

No love for Chaco and Pueblo Cultures? Great Zimbabwe?

Jackson

The neat thing about this display is the way it shows the exponential growth or expansion of civilization over time. Thanks for creating it. ………………. I also happened to notice the map shows the city of “St Louis” appearing on N. America at the year “1000 AD”. …. Really? ………. I also just wanted to point out that more recent analysis of evidence shows that the great Sphinx in Egypt is much much older than we’ve been taught. The wear on the stone has been determined to have been largely from water and not wind and sand.

Rosemary Fryth

Missing Reykjavik in Iceland.

Dieter Vandamme

I came accross this site looking for some visuals on industralisation and urbanisation. I was blown away by the material created and presented here. Absolutely beautiful work, so keep that up!
It’s interesting to see that cities first originate in regions with warm climates and only habitable around rivers. Perhaps due to the more difficult environment, people found themselves better off organising eachother and living together?

http://metrocosm.com Max Galka

Thanks Dieter! If you’re familiar with Jared Diamond, his book Guns Germs and Steel offers a very satisfying explanation for why civilization originated where it did. It’s line with your thoughts actually. The wide/flat geography of Europe / Asia has many people living in the same climates, which allowed them to share developments in domestication of plants / animals. Mesopotamia in particular had the benefit of two fertile rivers and a many animals that could be domesticated. Cows, goats, horses, pigs, sheep are all originally from that region.

basitlhr

nice! but i think there was huge geographical change in land which is not projected on map.